1. Field of Endeavor
The present invention relates to the field of non-destructive workpiece testing, and more particularly to a scanning device.
2. Brief Description of the Related Art
In the technology of thermal machines, especially steam or gas turbines, studs are frequently used for screwing together turbine casings which have a bore extending in the longitudinal direction in order to be able to heat up the stud separately, for example. Cracks can extend from this bore, which impair the mechanical strength of the stud which is under severe stress and can lead to serious consequences.
It has therefore already been proposed in the past to visually inspect such studs by an optical probe being inserted into the bore after preparatory cleaning of the bore and preparation of the inside surface (U.S. Pat. No. 7,531,770). A visual inspection of this type, however, is associated with considerable expenditure of time during preparation and execution, cannot be easily automated, and is comparatively unreliable because only the surface can be inspected.
There are additional devices known on the market for the inspection of such bores by ultrasound, which are referred to as “Stud Inspection Manipulators” (SIM) (Phoenix Inspection Systems Ltd., Warrington, UK). In the case of these known devices, the sensor head of the ultrasound device is fastened on one end of a rod which by the other end is connected to a first drive unit by which the rod can be rotated in a controlled manner around the longitudinal axis. The first drive unit in turn is mounted on a slide which by a controllable, second drive unit can be moved linearly on a rail in the longitudinal direction of the rod. This device allows a detailed, automated and reliable inspection of the body, but has the disadvantage that, owing to the comparatively large external dimensions, it is unmanageable during transportation and requires a lot of space on the inlet side of the bore and also is limited with regard to the axial scanning range because of the length of the rail.